Superior performance improvements in elite cyclists following short‐interval vs effort‐matched long‐interval training

Abstract

The purpose of this study was to compare the effects of 3 weeks with three weekly sessions (ie, nine sessions in total) of short intervals (SI; n = 9; 3 series with 13 × 30‐second work intervals interspersed with 15‐second recovery and 3‐minutes recovery between series) against effort‐matched (rate of perceived effort based) long intervals (LI; n = 9; 4 series of 5‐minute work intervals with 2.5‐minutes recovery between series) on performance parameters in elite cyclists (trueV˙normalO2max 73 ± 4 mL min−1 kg−1). There were no differences between groups in total volume and intensity distribution of training during the intervention period. SI achieved a larger (P < .05) relative improvement in peak aerobic power output than LI (3.7 ± 4.3% vs −0.3 ± 2.8%, respectively), fractional utilization of trueV˙normalO2max at 4 mmol L−1 [La−] (3.0 ± 5.8 percent points vs −3.5 ± 2.7 percent points, respectively), and larger relative increase in power output at 4 mmol L−1 [La−] (2.0 ± 6.7% vs −2.8 ± 3.4, respectively), while there was no group difference in change of trueV˙normalO2max. Improvements in performance measured as mean power output during 20‐minute cycling test were greater (P < .01) in SI compared with LI (4.7 ± 4.4% vs −1.4 ± 2.2%, respectively). Mean effect size of the improvement in the above variables revealed a small to large effect of SI training vs LI training. The data thus demonstrate that the present SI protocol induces superior training adaptations compared with the present LI protocol in elite cyclists.

Systemic and muscular responses to effort‐matched short intervals and long intervals in elite cyclists

“…The present study compared systemic and muscular responses to time‐ and effort‐matched SI and LI in elite cyclists. SI was associated with higher power output and longer working time above 90% of VO 2max and 90% of HR peak than LI, without increasing perceived exertion or [BLa − ], adding to and supporting knowledge from previous research 4,9,36 . In line with this, SI and LI were associated with differential responses of selected endocrine variables, with SI leading to more pronounced increases in testosterone and testosterone‐to‐SHBG ratios in blood immediately after the exercise and leading to prolonged cortisol responses.…”

“…Short intervals allowed elite cyclists to ride at higher power outputs and sustain longer periods at intensities above 90% of VO 2max and HR peak compared to LI. This was accompanied by a greater hormonal response, which might lead to superior training adaptations, as previously reported 9,36 . However, SI does not seem to induce greater muscle activation and does not lead to clear differences in mRNA responses.…”

“…SI was associated with higher power output and longer working time above 90% of VO 2max and 90% of HR peak than LI, without increasing perceived exertion or [BLa − ], adding to and supporting knowledge from previous research. 4,9,36 In line with this, SI and LI were associated with differential responses of selected endocrine variables, with SI leading to more pronounced increases in testosterone and testosteroneto-SHBG ratios in blood immediately after the exercise and leading to prolonged cortisol responses. Surprisingly, the two intervals led to similar degrees of muscle activation, measured as EMG rms, and were associated with similar mRNA responses in m. Vastus lateralis, with the exceptions of NHE1 mRNA levels.…”

“…The superior physiological responses to SI, including higher power output and longer time spent above 90% of VO 2max , has previously been associated with superior improvements in performance and performance indices in well-trained 9 and elite cyclists. 36 This essentially means that SI elicits more pronounced effects on determinants of performance such as VO 2max and fractional utilization of VO 2max . While the effects of SI on VO 2max largely resides on systemic cardiovascular adaptations, 12 its effects on fractional utilization of VO 2max likely involves muscle adaptations.…”

“…11,13 As for cortisol, the prolonged response to SI can be interpreted as exerting a negative effect on muscle cellular plasticity. 15 However, as long-term SI induces superior effects on performance, 9,36 the prolonged cortisol response may facilitate recycling of proteins and cellular structures that are damaged during exercise, resulting in a pool of free amino acids and other micronutrients, that in turn facilitate protein synthesis and cellular plasticity in the anabolic phase. 16 To date, the importance of such acute hormonal changes for long-term adaptations remains inconclusive, 10,15,16 and further research is warranted, including long-term interventions of similar designs to the present study, with more frequent collection of blood samples.…”